127

Endemic and cosmopolitan Upper Cretaceous agglutinated foraminifera of the western African margin, equatorial and central Atlantic

ANN HOLBOURN and WOLFGANG KUHNT Institut fUr Geowissenschaften der Christian-Albrechts-Universitat zu Kiel, Olshausenstr. 40, 0-24118 Kiel, Germany

ABSTRACT

Three distinct Late Cretaceous agglutinated foraminiferal associations, characterising palaeo­bathymetric settings from the inner shelf to the abyss, are recognised along shelf to basin transects of the western African margin (equatorial and central Atlantic). These groupings are supported by the results of a correspondence analysis on 177 samples from the Benue Trough in Nigeria, Wells CM2, CM4 and CMI0 offshore Senegal, DSDP Hole 367 in the Cape Verde Basin and ODP Hole 959 on the Cote d'Ivoire-Ghana Transform Margin.

1. A low diversity association dominated by organically cemented, coarsely agglutinated taxa, including Am1notium nkalagum, Kutsevella sp. 1 and Amll10baculites spp., is found in marginal marine sites, originally situated close to the palaeo-coastline (inner part of the Benue Trough in Nigeria, Wells CM2 and CM4 along the Casamance transect).

2. An agglutinated association of variable taxonomic composition is observed in open marine settings, situated on the present day continental shelf, but possibly at greater depth in the Late Cretaceous (Well CMI0, and distal parts of the Tarfaya Basin). Changes in taxonomic composi­tion appear related to fluctuations in the intensity of the clastic flux and/ or oxygen minimum zone. Intermittent occurrences of Galldryina laevigata, Gaudryina pyramidata, Reophax d. duplex, Ammomargillldina sp. 1, Hyperamll1ina spp., Haplophragmoides spp., Trochammina spp. and Textulariopsis spp. are recorded at Well CMI0, whereas in the Tarfaya Basin marked fluctu­ations occur in the relative abundance of Pseudoc/avulina c/avata, Gaudryina cretacea, Marssonella oxycona, Tritaxia capitosa, Spiroplectinella cretosa, Haplopllragmoides sp. A and Dorothia sp. l.

3. A high diversity organically cemented agglutinated association including Uvigerinammina jankoi, Karrerzdina con versa, Rzehakina spiroloculinoides, Rzehakina epigona, Rzelwkina inc/usa, Saccammina grzybowskii, Saccammina placenta, Hyperammina dilatata, Caudammina gigantea and Calldall1mina ovula characterises sub-CCD pelagic settings (DSDP Hole 367, ODP Hole 959).

Endemic agglutinated foraminifera are found in marginal marine assemblage and, to a lesser extent, in open shelf assemblages during regressive episodes. These endemic associations reflect the existence of limited connections with the open ocean in the shallower and more restricted parts of basins. Cosmopolitan deep-water agglutinated assemblages, with similar taxonomic composition in the North and South Atlantic occurred at least since the Santonian. These deep­water assemblages provide evidence for the existence of a rather uniform, oxic deep-water mass and an Atlantic ocean-wide deep-water circulation system since that time.

INTRODUCTION Upper Cretaceous benthic foraminiferal assem­blages from western African coastal basins bear a unique record of the palaeoceanographic evolution of the equatorial western African margin during the Late Cretaceous. Agglutinated foraminifera charac­terise a variety of marine settings along the western African margin of the equatorial Atlantic, from restricted inner neritic to sub-CCD abyssal depths. They provide useful biostratigraphic markers and palaeoenvironmental indicators, and may be used to constrain the palaeoceanographic history of the

margin, as it evolved from a transform margin set­ting to a passive stage during the Late Cretaceous and deep-water connections became established between the North and South Atlantic after the opening of the central Atlantic gateway. The distri­bution of Upper Cretaceous agglutinated foramini­fera in western African coastal basins is still poorly understood, due to a lack of published data and the absence of a unified benthic foraminiferal system­atic nomenclature. The few studies, which have been published to date, include the documentations of Upper Cretaceous agglutinated foraminifera from

In: Hart, M.B., Kaminski, M.A., & Smart, C.W. (eds) 2000. Proceedings of the Fifth International Workshop on Agglutinated Foraminifera. Grzybowski Foundation Special Publication, 7, 127-148.

128

DSDP 369 •

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Ann Holboum & Wolfgang Kuhnt

·30'

CALAJIAR F1..4HK

o''___-.;.;'ooi,;.. _.....;;200,;.j Km

GULF OF GUINEA ABYSSAL PLAIN

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Figure 1. Location map for the Benue Trough in Nigeria, the Casamance Shelf offshore Senegal, DSDP Site 367, DSDP Site 369, ODP Site 959 and the Tarfaya Basin in southern Morocco.

Nigeria by Petters (1979, 1982), from Gabon by Volat et al. (1996) and from ODP Hole 959 on the Cote d'Ivoire-Ghana Transform Margin (CIGTM) by Kuhnt et al. (1998).

The main objectives of this work are to document the taxonomy and to investigate the distribution of Upper Cretaceous agglutinated foraminifera in equatorial coastal basins of western Africa along a latitudinal transect extending from Nigeria to Morocco. Material available for this study includes samples from onshore sections of the Benue Trough in Nigeria, cuttings and cored sections from three com­mercial wells drilled on the inner/middle and outer shelf of the Casamance margin offshore Senegal, samples from DSDP Hole 367 in the Cape Verde Basin, samples from ODP Hole 959 on the CIGTM and samples from onshore sections of the Tarfaya Basin in southern Morocco (Figure 1). The study also includes taxonomic comparisons with benthic foraminiferal assemblages from DSDP Hole 369, off southern Morocco and with published reports from Gabon and Nigeria. The arrangement of studied localities along shelf to basin transects will help to clarify palaeobathymetric distribution patterns along the western equatorial African margin during the Late Cretaceous and will provide information on the sea level history of the margin.

LOCATION AND GEOLOGICAL SETTING Benue Trough, Nigeria Our samples were taken from five locations in the Benue Trough: the Gongila Formation in the Ashaka limestone quarry (Northern Benue Trough), the Pindiga Formation in the Pindiga creek, southwest of Pindiga village (Northern Benue Trough), the Nkalagu Quarry (Central Benue Trough), the Lokpanta (Central Benue Trough) and the Ngbanocha sections (Southern Benue Trough). The lithology and sample positions in the Ashaka and Pindiga sections are shown in Figure 2. Similar information for the Nkalagu Quarry and the Lokpanta and Ngbanocha sections can be found in Holbourn et al. (1999b).

The Pindiga and Gongila Formations in the Northern Benue Trough consist of alternating marine limestone and shale/mudstone about 30 m thick for the Ashaka section and 60 m thick for the Pindiga section. The lower part of the Gongila Formation overlies the fluvio-deltaic sequence of the Bima sandstone and reflects the global late Cenomanian transgressive phase. It consists mainly of biogenic shallow water limestones, dated as late Cenomanian to early Turonian from their rich ammonite content (Popoff et al., 1986). The upper part of the Gongila Formation is characterized by a

Upper Cretaceous agglutinated foraminifera of the western African Margin 129

ASHAKA & PINDIGA SECTIONS (NORTHERN NIGERIA)

Lithology Samples PINDIGA

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3/3-28

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Figure 2. Lithology and positions of studied samples in the Asnaka and Pindlga sectIOns in the Northern Benue Trough, Nigeria. Stratigraphy based on the ammonite zonation of Popoff et al. (1986).

sequence of dark grey fissile shales in which some thin lumachelle beds are intercalated, probably representing tempestites. Ammonites within these limestone layers indicate a middle Turonian age (Popoff et al., 1986)_

The Pindiga Formation is located approximately 100 km south of the Gongila-Ashaka area and rep­resents part of the sedimentary fill of the Pindiga­Gombe Basin (Allix, 1983), where the rates of sedi­mentation were high from the Coniacian to the Maastrichtian (Popoff et al., 1986). The outcrop studied consists of a predominantly shaly sequence with calcareous concretions and intercalations of biodetritallimestones. The ammonite content in the Pindiga section concentrated in the limestone layers, indicates a late Cenomanian to early Turonian age (Popoff et al., 1986). Generally, the Cenomanian/ Turonian of the Pindiga section is thicker, more complete and less condensed than the Gongila Formation in the Ashaka Quarry.

The Turonian to Coniacian sediments from the Central and Southern Benue Trough consist of marginal clastic sequences on the edge of the basin and of black, laminated organic rich calcareous marls and limestones, overlain by fine grained sand­stones, lumachelle beds and limestones with hard­grounds and tempestites in the central part of the basin. This sedimentary sequence corresponds to the

late Cenomanian/Turonian global eustatic sealevel rise, which resulted in the build-up of a wide shelf platform on the western flank of the basin, where condensed sections, tempestites and tidalites can be observed (Ojoh, 1988). After the Santonian compres­sive phase the uplifted region was then subjected to an important erosional stage during the Campanian (Ojoh, 1988). The palaeoenvironments of the Central and Southern Benue Trough have been interpreted as coastal areas to the north ranging to a deep outer shelf with shelf slope transition to the south (Kuhnt et al., 1990). Two major lithostratigraphic units are recognised in the Turonian to Coniacian sedimentary succession (Ojoh, 1988):

1. Nara Unit (Turonian): The lower part of this unit is characterized by black, laminated organic­rich calcareous marls and limestones, with rich early Turonian inoceramid faunas (Inoceramus opalensis, Sergipia spp., determined by E.G. Kauffmann). The microfauna in this sequence is characterized by rich, purely planktonic foraminiferal assemblages of the Cenomanian/ Turonian transition, which contain the zonal species Whiteinella archaeocretacea. These sediments are considered as the local expression of the global Cenomanian/Turonian boundary anoxic event (CTBE). The middle and upper part of the unit consists of fine-grained sandstone, lumachelle beds, tempestites, limestones and hardgrounds, and com­monly exhibits characteristic features of condensed sequences. Typical ammonites are Fagesia involuta, Pseudotissotia wallsi, Hoplitoides sp. and Coilopoceras d. requienianum of middle to late Turonian age (Ojoh, 1988).

2. Awgu Unit (Coniacian): This unit consists of platform carbonates and dark, silty argilites or fine­grained calcareous sandstones with Gaudryiceras sp., Inoceramus lusatiae and Inoceramus schioenbachi (Ojoh, 1988).

Casamance Shelf, offshore Senegal The Senegal Basin is the largest of the Mesozoic West African basins, extending over Mauritania, Senegal, Gambia and Guinea Bissau and offshore to the Cape Verde Islands. Several exploration wells were drilled on the Casamance Shelf, offshore Senegal, which recovered extensive Upper Cretaceous sedimentary sequences. The most sea­ward of the wells CM10 is situated close to the shelf edge, while Wells CM2 and CM4 are in more proxi­mal locations (Figure 1)_ Thick Turonian to Maastrichtian sedimentary sequences were recov­ered at Well CM2 (over 1600 m), Well CM4 (over 1200 m) and Well CMlO (over 1200 m). The Turonian at Well CM2 is approximately 150 m thick and con­sists of dark brown and bituminous clays. The Coniacian to Santonian is approximately 350 m thick and corresponds to dark claystones interca­lated with calcareous and occasionally sandy layers. Similar lithological sequences were recov

130 Ann Holboum & Wolfgang Kuhnt

Figure 3. Lithology and positions of studied samples in the Sebkha Tah section in southern Morocco.

ered at Well CM4, where the Turonian is nearly 100 m thick and the Coniacian to Santonian just under 200 m. At Well CM10 the Turonian is approximately 150 m thick and the Coniacian to Santonian, which corresponds to dark claystones and calcareous clay­stones with some lighter clayey calcareous layers, is 100 m thick. The Campanian to Maastrichtian suc­cessions at the three sites consist of dark claystones with silty, sandy or calcareous intervals (approx­imately 400 m at Wells CM2 and CM4 and 150 m at Well CMI0) and an increasing silt and sand content towards the top of the successions. Details of the lithology and the positions of the studied samples from these wells can be found in Holbourn et al . (1999a) .

Upper Cretaceous benthic foraminiferal assem­blages in cutting samples from offshore Casamance Maritime 10 (Well CMI0), off Senegal were docu­mented by Ly & Kuhnt (1994). These authors inter­preted the palaeoenvironment as a middle-outer shelf subjected to an intensified oxygen minimum zone under upwelling conditions during the Late Cretaceous. An integrated study of the benthic foraminiferal assemblages, clay minerals, kerogen types and carbonate microfacies in core and cutting samples from four offshore wells along a transect across the Casamance margin, extending from the the inner shelf to the abyss was carried out by Holbourn et al. (1999a). Results from this study pro­vided evidence that a productivity-driven oxygen minimum zone (OMZ) was established along the Casamance margin during most of the Late

Cretaceous. During sea level highstands at the Cenomanian / Turonian boundary and in the early Campanian the OMZ intensified and expanded to reach more proximal environments of the inner shelf (Wells CM2 and CM4).

Tarfaya Basin, southern Morocco The Tarfaya Basin is an Atlantic coastal basin extending along southern Morocco between latitudes 2S'N and 24'N, which has remained tectonically stable since the Cretaceous. Marginal marine sedi­ments of Albian age are exposed along the northern edge of the basin. Extensive Upper Cretaceous sedi­mentary successions of Cenomanian to Turonian age are found along the coast and in the central part of the basin. Bituminous marls were deposited in the central part of the Tarfaya Basin during the Turonian in an open shelf setting, in water depth in the order of 200 to 300 m (Kuhnt e/ al., 1990). These marls have high values of Total Organic Carbon (TOC) and are characterised by abundant planktonic foraminifera. Benthic foraminifera are either absent or consist of extremely low diversity calcare­ous assemblages .. showing cyclic variations in abun­dance. These sediments partly correspond to the global anoxic event at the Cenomanian / Turonian boundary (CTBE). Approximately 50 km east from the town of Tarfaya, in the central part of the basin, a 20 m sedimentary succession of early Campanian age is exposed at Sebkha Tah. Details of the lithology and the positions of the studied samples from this section cat> be found in Figure 3 and in

I

Upper Cretaceous agglutinated foraminifera of the western African Margin 131

Holbourn et ai. (1999b). The Sebkha Tah succession consists of alternating dark and light marl layers, which show little alteration and contain diverse benthic foraminiferal assemblages including a large proportion of agglutinated forms. A preliminary investigation of the benthic foraminiferal assem­blages, clay minerals and kerogen types indicated that the original environment of deposition was an outer shelf or upper slope receiving a high phytode­tritus flux derived from enhanced surface productivity (Holbourn et al., 1999b).

DSDP Holes 367, 369 and ODP Hole 959 DSDP Hole 367, was drilled in a water depth of 4748 m in the Cape Verde Basin, at 12°29.2'N, 20 0 02.8'W, approximately 330 km west of Wells CM2, CM4 and CMI0. DSDP Hole 367 and the Casamance wells form an East to West coast to basin transect across the Senegal margin. DSDP Hole 369 was drilled in a water depth of 1752 m on the conti­nental slope off southern Morocco at 26° 35.5'N, 14° 59'W, and is the offshore continuation of the Tarfaya transect. Lithological and sedimentological descriptions of the cores recovered from DSDP Sites 367 and 369 can be found in Lancelot, Seibold et al. (1977). ODP Hole 9590 was drilled in a water depth of 2090.7 m on the northern flank of the Cote d'lvoire-Ghana marginal ridge at 3°37.656'N, 2°44.149'W, on a small plateau close to the top of the Cote d'lvoire-Ghana marginal ridge. This loca­tion already belongs palaeogeographically to the South Atlantic and may be roughly considered as an offshore prolongation of the Nigerian transect. Lithological and sedimentological descriptions of the cores recovered from this site can be found in Mascle, Lohman, Clift et al. (1996).

METHODS For micropalaeontological studies, the samples were dried, weighed, soaked in distilled water and wet­sieved through a 63 Jl.m (#230 mesh) screen; then, the residue was dried. Consolidated samples were first treated with a buffered 5% hydrogen peroxyde solution to help break up before sieving. In most cases the hydrogen peroxyde treatment did not lead to complete disintegration of the clay. These samples were dried and soaked in a concentrated anionic tenside solution (REWOQUAT of REWO Chemie, Steinau an der StraBe, Germany), which usually disintegrated even slightly silicified sam­ples. In DSDP lOOP core samples and commercial cuttings the complete residue was picked for benthic foraminifera. Most of the onshore samples and large core samples from commercial wells were split with a standard Otto-splitter. Fragments of tubular species were counted as one individual. Indeterminable fragments or extremely deformed specimens were picked but not included in the counts. Faunal occurrences only were recorded for cutting samples. The foraminiferal slides are housed in the

Micropalaeontology collections of the Institut fUr Geowissenschaften at the Christian Albrechts University in Kiel. Electron micrographs were made on a Camscan SEM at the Institut fUr Geowissen­schaften at the Christian Albrechts University in Kiel.

Correspondence analysis was carried out using the correpondence factor analysis software package ECOLOGIX written in 1982 by M. Rioux (Montpellier University). ECOLOGIX was run on a CRAYVAX computer at the University of Kiel. Quantitative distribution charts of agglutinated foraminifers were combined into a coded matrix for a total of 177 samples with frequency counts of 144 taxa of agglutinated foraminifera (Table 1). Original counts of benthic foraminifera were converted into frequency counts as follows:

Number of foraminifera

1-3

4-10

11-50

>50

Frequency

10rr

20rf

30rc

4 or a

A more detailed description of the application of correspondence analysis to micropalaeontological data sets is given in Saint-Marc & Berggren (1988) and Kuhnt & Moullade (1991).

FAUNAL ASSEMBLAGES The available set of samples can be grouped into three main settings according to their palaeogeo­graphic position: (1) marginal marine sites, which were situated close to the palaeo-coastline (inner part of the Benue Trough in Nigeria, Wells CM2 and CM4 along the Casamance transect); (2) open marine settings, situated on the present day continental shelf, but which may have been at greater depth in the Late Cretaceous (outer part of the Benue Trough, Nigeria; Well CMI0, and distal parts of the Tarfaya Basin); (3) deep marine sites (ODP Hole 959 on the CIGTM, DSDP Hole 367 in the Cape Verde Basin, and DSDP Hole 369 off southern Morocco). These initial palaeogeographical settings are reflected by the grouping of agglutinated foraminifera in the correpondence analysis, which was run on a total of 177 samples from the Benue Trough in Nigeria, Wells CM2, CM4 and CMI0 off­shore Senegal, DSDP Hole 367 and ODP Hole 959 (Table 1; Figures 4 and 5).

Discrimination of assemblages The correspondence analysis shows a distinct pat­tern in the distribution of agglutinated foraminifera at the five studied locations (Figures 4 and 5). The agglutinated assemblages from DSDP Hole 367 and ODP Hole 959 exhibit little variance in their posi­tion on the correspondence factor axes and differ

132

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markedly from the assemblages of Nigeria (Ashakar, Pindiga, Ngalagu, Lokpanta and Ngbanocha sections) and the Casamance Shelf (Wells CM2, CM4 and CMI0). The assemblages from Nigeria and from the most proximal wells on the Casamance Shelf (CM2 and CM4) plot close together but still exhibit a significant degree of variability. The assemblages from the most distal well on the Casamance Shelf (CMI0) vary markedly in their position along the second factor axis and have a distinct composition. Thus, the correspondence analysis allows three main assemblages to be recognised (Figures 4 and 5): (1) a deep-sea assemblage at DSDP Hole 367 and ODP Hole 959 with a well defined, diverse composition, (2) an outer shelf assemblage (Well CMlO), with a highly

Ann Holbourn & Wolfgang Kuhnt

variable composition and (3) a marginal marine low diversity assemblage (Nigeria, Wells CM2 and CM4), showing some variability in composition.

Palaeoenvironmental interpretation of assemblages Marginal marine assemblages Upper Cretaceous benthic foraminiferal assem­blages from inner shelf settings of the Benue Trough, Nigeria (Ashaka and Pindiga sections, Nkalagu Quarry, Lokpanta and Ngbanocha sections) and the Casamance Shelf, Senegal (Wells CM2 and CM4) exhibit extremely low diversity and are charac­terised by agglutinated foraminifera with coarsely agglutinated, organically cemented tests. Characteristic taxa are Ammotium nkalagum, Ammotium barnum, Kutsevella sp. I, Trochammina sp. 1 and Ammobaclliites spp. There is significant variation in the relative proportions of these taxa, probably reflecting different ecological preferences in a shallow and variable environment. The sedi­ments from these localities, which typically contain abundant Type III organic matter and clay mineral assemblages dominated by the detrital minerals chlorite, illite and kaolinite, also indicate a shallow inner shelf setting receiving a high clastic input from the nearby continent (Holbourn et al., 1999b). Benthic foraminiferal assemblages of simi­lar composition Were documented by Volat et al. (1996) from the Upper Cretaceous of Gabon and were interpreted by these authors as diagnostic of shallow, restricted, neritic conditions .

Outer shelf assemblages Coniacian to Maastrichtian assemblages from Well CMI0 on the Casamance Shelf generally contain buliminid associations but are intermittently domi­nated by agglutinated taxa, including Gaudryina laevigata, Galldryina pyramidata, Reophax d. duplex, AmmomargilZlllina sp. I, Hyperammina spp., Haplaphragmoides spp., Trochammina spp. and Textulariopsis spp. The palaeoenvironment of this area of the CasamanCe Shelf was interpreted as a middle-outer shelf subjected to an intensified OMZ during most of the Late Cretaceous (Ly & Kuhnt, 1994; Holbourn et al., 1999b). The intermittent occurrenCe of large numbers of agglutinated taxa within the assemblages may reflect episodic increases in terrigenous flux from mainland Africa and/or fluctuations in the development of the OMZ on the outer shelf. Changes in the intensity of the clastic flux and OMZ Were probably the main factors controlling the distribution of agglutinated foraminiferal assemblages on the Casamance Shelf during the Late Cretaceous.

The composition of the Lower Campanian benthic foraminiferal assemblages from the Sebkha Tah section in the Tarfaya Basin differs markedly from that of the Casamance Shelf. This may be partly a reflection of the pelagic, carbonate-dominated sed­imentation with low terrigenous flux in the Tarfaya Basin. The assemblages show variations in vertical

Upper Cretaceous agglutinated foraminifera of the western African Margin 133

distribution, which appear related to changes in TOC values. In the lighter intervals at the base of the section (0 to 11.5 m) Pseudoclavulina clavata, Gaudryina cretacea, Marssolle/la oxycona, Tritaxia capitosa, Spiropiectillella cretosa, Haplophrag­lIloides sp. A and Dorotilia sp. 1 are recorded along with abundant nodosariids and gavelinellids. A marked change in assemblage composition and in the diversity of agglutinated foraminifera occurs in the darker interval above (11.5 to 15 m), where TOC reaches maximum values. The assemblages become strongly dominated by buliminids and bolivinids and by the agglutinated species Haplophragmoides sp. A and Spiroplectille/la cretosa, while other agglutinated forms disappear. In the upper part of the section (15 to 20 m), where TOC values decrease, the relative proportion of buliminids and bolivinids declines and some agglutinated forms, initially pre­sent in the lower part of the section, reappear. The abundance of planktonic foraminiferal tests, includ­ing large numbers of heterohelicids and the occur­rence of radiolarians in the assemblages as well as the high content of Type II organic matter in the sediments suggest high surface water productivity (Holbourn et al., 1999b). Changes in the composition of the assemblages probably reflects changing oxy­genation levels at the sediment/water interface in response to fluctuations in carbon flux rates to the seafloor and/ or changing bottom water circulation.

Deep-sea assemblages The Campanian to Maastrichtian benthic foramini­feral assemblages from DSDP Hole 367 in the Cape Verde Basin and from ODP Hole 959 on the ClGTM are characterised by organically cemented Deep­Water Agglutinated Foraminifera (DWAF) typi­cally found in Upper Cretaceous sediments deposited below the CCD in the North Atlantic (Kuhnt et al., 1998). Characteristic species are Uvigerillammina jallkoi, Karrerlliilla con versa, Rzelwkina spiroloclllilloides, Rzehakina epigona, Rzelwkilla illc/usa, Saccammina grzybowskii, Saccammina placenta, Hyperammina dilatata, Caudammina gigantea and Caudammilla ovula.

The Campanian to Maastrichtian assemblages from ODP Hole 959 reflect well ventilated, oligo­trophic conditions in an increasingly deeper bathyal to abyssal setting, except for a short interval in the early Campanian. This interval, characterised by low diversity assemblages of opportunistic deep­water benthic foraminifera ("Biofacies B"), proba­bly corresponds to the Early Campanian Event (Kuhnt et al., 1998). This palaeoceanographic event is recorded at various North Atlantic DSDP and ODP holes and in outcrop sections in Spain, Italy, Romania, Germany and Morocco. It may represent a short term warming episode during which the increased formation of warm saline bottom waters led to changes in the deep circulation of the Central Atlantic. This event is not registered at DSDP Hole

367, where stratigraphic resolution is poor due to spot coring.

PALAEOBIOGEOGRAPHY Coniacian to Santonian marginal assemblages from the Casamance Shelf, dominated by Ammotiul1l Ilkalaglllll, A III lIlotili III bOrll II Ill, Klltsevella sp. I, Troc/wlIllllilla sp. 1 and Amlllobaclliites spp., closely resemble Turonian to Coniacian assemblages from the Benue Trough, Nigeria and assemblages docu­mented by Volat et al. (1996) from Gabon. The com­position of the assemblages suggests that a signifi­cant degree of endemism existed in these coastal basins, and points to the existence of migration bar­riers restricting faunal distribution during the Turonian to Santonian. By contrast, the occurrence of cosmopolitan agglutinated taxa in assemblages from the more distal Well CMI0 on the Casamance Shelf, indicates that more open marine conditions prevailed on the outer shelf from the Coniacian to Maastrichtian with open connections to the North and South Atlantic Ocean.

The upper bathyal agglutinated foraminifera from the Sebkha Tah section of the Tarfaya Basin are cosmopolitan, reflecting the existence of a well established oceanic circulation in this part of the basin. The Campanian to Maastrichtian assem­blages from DSDP Hole 369 at the foot of the conti­nental slope, on a direct transect from the Tarfaya Basin, show high faunal diversity but differ in composition from the assemblages of the Sebkha Tah section. This is probably due to the reduced phytodetritus flux to the seafloor as particles sink to greater depths further out into the basin. Oxygen is consequently less depleted at these depths and the OMZ no longer intersects the seafloor. Virtually all of the species observed at Site 369 are cosmo­politan, providing further evidence for the existence of a cosmopolitan deep-water benthic foraminiferal fauna in the Late Cretaceous Atlantic Ocean.

Campanian to Maastrichtian assemblages from ODP Hole 959 and Coniacian to Maastrichtian assemblages from DSDP Hole 367 consist exclusively of DWAF, indicating that these sites were below the CCD. Changes in the composition of lower Turonian to lower Campanian assemblages at ODP Hole 959 reflect the subsidence history of this site during the active stage of the ClGTM, from a shelf setting to sub CCD depths. The Coniacian to Santonian benthic foraminiferal assemblages from ODP Hole 959 on the CIGTM are initially domi­nated by buliminid associations (Holbourn & Kuhnt, 1998). However, an overall increase in benthic foraminiferal diversity and in the proportion of OW AF in the Santonian assemblages signals a decrease in carbon flux and the gradual subsidence of the seafloor. The similarity in the composition of DWAF agglutinated assemblages from DSDP Hole 367, ODP Hole 959 and other DSDP and ODP holes in the North Atlantic provide evidence that a deep

134

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~ Trochammina. sp. 1

Ann Holboum & Wolfgang Kuhnt

TARFAYA

CM10

. aetacea • Haploph. sp. A

:- P. clavata

959

~ S. cretosa T. capitcsa Hyperamm"naspp.

-Textulariopsis- spp. e ?Haploph. sp. 1

:::E Hap/oph. ",. 2

U G.pyramidata G.laevigata

oxygen minim um (buliminid assemblages only)

369

... '" '" .. '" .... '"

367 Turorian Gi

> .!!

am pan Ian " " ..

E ::I

.5 c: E c: CP C> >->< 0

C. gigantea C.ovulum R. epigona R. spirolo cu/ina ides R. inc/uSa K. ron versa U. jankoi S. placenta H. dilat;ta

Figure 6. Late Cretaceous associations of agglutinated foraminifera in shelf to basin transects of the western equatorial African margin.

water circulation system was well established between the North and South Atlantic by the end of the Santonian.

CONCLUSIONS Three distinctive Late Cretaceous associations of agglutinated foraminifera, characterising palaeo­bathymetric settings from the inner shelf to the abyss, are recognised in shelf to basin transects along the western equatorial African margin (Figure 6).

1. A low diversity association dominated by coarsely agglutinated taxa with organic cement including Ammotium nkalagu1l1, Kutsevella sp. 1 and Ammobaculites spp. is typically found in marginal marine environments of Nigeria, Gabon and Senegal. This association exhibits a high degree of endemism, and reflects limited connections with the open ocean in the shallower and more restricted parts of equatorial African basins.

2. The composition of the agglutinated associa­tion in shelf and upper slope environments is more variable. Intermittent occurrences of Galldryilla laevigata, Gaudryina pyramidata, Reophax d. duplex, A mm onzargi n llli na sp. 1, Hype ra 111 m ina spp., Haplophragmoides spp., Yrochammilla spp. and Yextulariopsis spp. on the Casamance Shelf probably reflect changes in terrigenous sedimenta­tion and/ or periodic contraction or expansion of the OMZ. Changes in the relative abundance of Pseudoclavlllina clavata, Galldryina cretacea,

Marssonella oxycona, Yritaxia capitosa, Spiroplectinella cretosa, Haplophragmoides sp. A and Dorothia sp. 1 in the Tarfaya Basin appear related to fluctuations in the organic matter export flux from enhanced surface production, affecting oxygen resources at the seafloor. Shelf and upper slope assemblages from the Senegal Basin and Tarfaya Basin contain large numbers of cosmopolitan taxa, providing evidence that open connections existed between these coastal basins and the North and South Atlantic.

3. A Campanian to Maastrichtian deep-sea asso­ciation is characterised by cosmopolitan OW AF including Uvigerinammina jankoi, Karrerulina con versa, Rzehakina spiroloculinoides, Rzehakina epigona, Rzehakina inclusa, Saccammina grzybow­skii, Saccammina placenta, Hyperammina dilatata, Calldammina gigantea and Caudammina oVilla. Diversity is generally high, reflecting well ventilated, oligotrophic conditions in a pelagic set­ting, except in the lower Campanian of ODP Hole 959. This impoverished early Campanian aggluti­nated biofacies probably indicate a major change in the deep circulation system of the Central Atlantic.

Endemic agglutinated foraminifera are observed only in marginal marine assemblages and, to a lesser extent, in open shelf assemblages during regressive periods. Cosmopolitan deep-water agglutinated assemblages, with similar taxonomic composition in the North and South Atlantic occurred at least since

Upper Cretaceous agglutinated foraminifera of the western African Margin 135

the Santonian. These deep-water assemblages pro­vide evidence for the existence of a rather uniform, oxic deep water mass and an Atlantic ocean wide deep-water circulation system since that time.

TAXONOMY Generic definitions follow Loeblich & Tappan (1987). Quotation marks are used for tentative generic assignments in cases where the definition of the genus does not take wall structure into account. Open nomenclature is used for taxa that do not closely match published descriptions. The following abbreviations are used: d. for taxa similar to a known species but different

in some detail. sp. 1, 2 ... for species which do not match published

descriptions. sp. and spp. for taxa not determinable at the speCific level.

OW AF from DSDP Holes 367 were previously documented by Krashenninikov & Pflaumann (1977). Updated taxonomic references for these taxa can be found in Holbourn et al. (1999a). DWAF from ODP Hole 959 were documented by Kuhnt et al. (1998). The taxonomic concept of these forms follows Kuhnt & Kaminski (1990) and Kaminski & Geroch (1993).

Ammobaculites sp. 1

Plate 4, Figs 7-9.

Diagnostic features. Coarsely agglutinated test with well developed initial planispiral whorl and broad, curved or rectilinear, evolute portion. Six or more chambers surround a distinct umbilicus in the planispire. Four or more low, wide chambers in the evolute portion are separated by depressed sutures. Remarks. Resembles Ammabaculites stephensani Cushman illustrated by Volat et al. (1996, pl. 9, fig. 156). Range and Occurrence. Late Cretaceous in Well CM2, Casamance Shelf, Senegal.

Ammobaclliites sp. 2

Plate 3, Fig. 8.

Diagnostic features. Coarsely agglutinated test with small initial planispiral whorl and long, nar­row, curved or rectilinear, evolute portion. Range and Occurrence. Late Cretaceous in Well CM2, Casamance Shelf, Senegal.

Ammomarginulina sp. 1

Plate 5, Figs 1-3.

Diagnostic features. Small, strongly compressed, coarsely agglutinated test showing tendency to become uncoiled. Chambers around the distinct umbilicus numerous and separated by depressed, oblique sutures. Remarks. Most of our specimens do not have a well­developed evolute portion.

Range and Occurrence. Late Cretaceous in Well CM10, Casamance Shelf, Senegal.

Ammotillm bOnlll11l Petters, 1982

Plate 7, Figs 2-5.

Ammotillnl bornum Petters, 1982, pI. 2, figs 10-12.

Remarks. Differs from A. llkalagum and A. Ilwaium by its narrow, elongate shape and its small, involute initial portion. Intermediate forms between A. barnllm and A. nkalagum are found. Range and Occurrence. Albian to Santonian in central West Africa (petters, 1982).)

Ammotium nkalagllm Petters, 1982

Plate 5, Figs 4-7; Plate 6, Figs 9-12.

Ammotill111 nkalagu11l Petters, 1982, pI. 2, figs 4-6. Ammotium nkalagum Petters. - Volat et aI., 1996, pI. 9, figs

158-161.

Remarks. Differs from A. mualum by its wider and flabelliform shape. Our specimens are morphologi­cally similar to modern Ammatillm, typically found in neritic, brackish environments (J. Nagy, pers. comm., 1997). Range and Occurrence. Turonian to Santonian in cen­tral West Africa (petters, 1982). Recorded in the Turonian from Gabon (Volat et al., 1996).

Ammotium nwaillm Petters, 1982

Ammotium nwalllIn Petters, 1982, pI. 2, figs 1-3.

Remarks. Differs from A. nkalagum and A. barnum by its broad, ovate test, tapering towards the final chamber and its fairly smooth wall. Range and Occurrence. Turonian to Santonian in central West Africa (petters, 1982).

Dorothia sp. 1

Plate 1, Figs 10-11.

Diagnostic features. Elongate, gently flaring, smoothly cemented test with last two chambers larger and markedly inflated. Range and Occurrence. Occurs in the lower Campanian in the Tarfaya Basin, Morocco.

Gaudryina cretacea (Karrer, 1870)

Plate 2, Figs 8-9 & 12.

Vernelli/ina eretaeea Karrer, 1870, pI. 1, fig. 1. Galldryfna eretacea (Karre~). - ~uhnt, 1987, pI. 4, fig: 3; pI.

36, fIgs L7-1O. - Almogl-Labm et al., 1990, pI. 1, fig. 4. -Bolli et al., 1994, figs 23.26.

Gaudryina laevigata Franke, 1914

Plate 3, Figs 1 & 3.

Gaudryina laevigata ~ranke, 1914, pI. 27, figs 1-2. - Ly & Kuhnt, 1994, p1. 2, figs 5-7.

Galldryina pyramidata Cushman, 1926

Plate 3, Figs 2 & 4.

136

Gaudryina laevigata Franke var. pyramidata Cushman, 1926, pI. 16, fig. 8. Gillidryina pyramidata Cushman. - Ly & Kuhnt, 1994, pI. 2, fig. 14.

?Haplopltrag11loides sp. 1

Plate 3, Figs 9-10. Haplophragmoides exeavatus Cushman & Waters. - Ly &

Kuhnt, 1994, pI. I, figs 9-10. Haplophragmoides gr. walteri (Grzybowski, 1898). - Volat

rt al., 1996, pi. 7, figs 128-137.

Diagnostic features. Planispiral, involute test with slighty lobulate, acute periphery. Ten to eleven chambers in the last whorl, inflated around the umbilicus and flattened at the periphery, are sepa­rated by depressed, curved or sigmoidal sutures forming a distinctive stellate pattern around the umbilicus. Wall is finely agglutinated with a smooth, polished finish. Remarks. Wall shows a distinct alveolar structure. A detailed study of the wall structure is necessary to determine the generic affiliation of this taxon. Range and Occurrence. Campanian-Maastrichtian in Gabon (Volat et al., 1996). Late Cretaceous in Well CM10, Casamance Shelf, Senegal.

Haplaphragmoides sp. 2

Plate 3, Figs 6-7.

Diagnostic features. Inflated, involute test with nine or more inflated chambers in the last whorl, very rounded periphery and distinct, depressed umbilicus. Remarks. Specimens are often compressed and deformed through diagenesis. Closely resembles Haplophragmoidcs il11pensus Martin, although our specimens are coarser-grained than the one illus­trated by McNeil & Caldwell (1981, pI. 11, fig. 9). Appears to have a deeper umbilicus and more numerous chambers than Haplaphragmoides impcll­SllS Martin, figured by Volat ct al. (1996, pl., 7, figs 107-116). Range and Occurrence. Campanian-Maastrichtian in Gabon (Volat et al., 1996). Late Cretaceous in Well CMI0, Casamance Shelf, Senegal.

Haplopltragmoides sp. A

Plate I, Figs 3 & 5-8.

Diagnostic features. Involute to slightly evolute, coarsely agglutinated test with eight to eleven inflated chambers in the last whorl, round periphery and marked open umbilicus. Range and Occurrence. Occurs in abundance in sam­ples with highest TOC values in the lower Campanian of the Tarfaya Basin, Morocco.

Hyperammina spp.

Plate 4, Figs 1 & 5.

Ann Holboum & Wolfgang Kuhnt

Remarks. Hyperammina represent 50% or more of all tests in Coniacian to Santonian sediments of Well CMI0 on the Casamance Shelf.

KlItsevella sp. 1

Plate 5, Figs 8-13.

Diagnostic features. Compressed, evolute, coarsely agglutinated test showing tendency to become uncoiled with inflated chambers separated by depressed sutures. Remarks. Brown organic lining visible in the inner whorls of some tests. Oval, areal aperture rarely visible. Range and Occurrence. Late Cretaceous in Well CM2, Casamance Shelf, Senegal.

Marssonella oxycona (Reuss, 1860)

Plate 2, Figs 13-15. Galldryil1a oxyeol7a Reuss, 1860, pi. 12, fig. 3. MaJ'ssol1el/a oxycol1a (Reuss). - Bartenstetn & Bolli, 1986, pI.

2, figs 6-7. Marssol1ella oxycona oxyeona (Reuss). - Bolli et al., 1994, figs

25.5-6.

Notltia robusta (Grzybowski, 1898)

Plate I, Figs 1-2. Dendrophyra robusta Grzybowski, 1898, pI. 10, fig. 7. Rlzabdammina roblls/a (Grzybowski). - Volat e/ al., 1996, pI.

2, figs 13-14.

Plectina len is (Grzybowski, 1896)

Plate 4, Fig. 18.

Sphopleeta lellis Grzybowski, 1896, pI. 9, figs 24-25. Plee/Illa ICl1is (Grzybowski). - Volat et al., 1996, pI. 11, figs

207-209.

Pselldoclavulina clavata Cushman, 1926

Plate 2, Figs 10-11. PSClldoclavlIlil1a clavata Cushman, 1926, pI. 17, fig. 4.

Reopltax cf. duplex Grzybowski, 1896

Plate 4, Figs 2-3. d. Reopllax dl/plex Grzybowski, 1896, 8, figs 23-25. d. Reoplwx duplt'x Grzybowski. - Ly & Kuhnt, 1994, pI. I,

figs 1-4, text-figs 3/1-19 & 4/1-7.

Reopltax globosus Sliter, 1968

Plate 4, Fig. 4.

Reophax globoslls Sliter, 1968, pI. 1, fig. 12. . Reophax globoslls Sliter. - Ly & Kuhnt, 1994, text-fIg. 4/10.

Spiroplectammina citicoana Lalicker, 1935,

Plate 4, Fig. 19. Syiropleetal7ll1lina c/zieoal1a Lalicker, 1935, pI. I, figs 8-9. Quasispiropleetammina ehicoana (Lalicker). - Bolli et al.,

1994, figs 21.28-29.

Spiroplectinella cretosa (Cushman, 1932)

Plate 2, Figs 4-7.

Upper Cretaceous agglutinated foraminifera of the western African Margin 137

Spiroplectallllllina laevis (Roemer) var. cretosa Cushman, 1932, pI. 11, fig. 3.

Spiroplectammina laevis Cushman. - Almogi-Labin et al., 1990, pI. 1, figs 1-3.

Spiroplectamlllina cretosa Cushman. - Hanzlikova, 1972, pI. 10, fig.9.

"Textulariopsis" sp. 1

Plate 4, Figs 14-15.

Diagnostic features. Elongate, narrow, strongly com­pressed, finely agglutinated test with slightly diverging sides. Inflated, numerous chambers are separated by fine, depressed sutures. Range and Occurrence. Late Cretaceous in Well CM10, Casamance Shelf, Senegal.

"Textulariopsis" sp. 2

Plate 4, Figs 12-13.

Diagnostic features. Large, elongate, finely aggluti­nated test with rounded periphery and markedly diverging sides. Ten to 15 inflated chambers in the last whorl are separated by fine, slightly depressed sutures. Range and Occurrence. Late Cretaceous in Well CM10, Casamance Shelf, Senegal.

"Textlllariopsis" sp. 3

Plate 4, Figs 10-II.

Diagnostic features. Elongate, compressed, test with lobulate, rounded periphery and strongly diverging sides. Twelve to fifteen wide, low, inflated cham­bers in the last whorl are separated by distinctly depressed, curved sutures. Wall is fine to medium­grained and noncalcareous. Range and Occurrence. Late Cretaceous in Well CM10, Casamance Shelf, Senegal.

Tritaxia capitosa (Cushman, 1933)

Plate 1, Figs 9 & 12-13; Plate 2, Figs 1-3. Galldryinella capitosa Cushman, 1933, pI. 5, fig. 8. Pselldogalldryinella capitosa (Cushman). - Olsson & Nyong,

1984, pI. 4, figs 6-8.

Trochanl1nilla sp. 1

Plate 4, Figs 16-17.

Diagnostic features. Large medium to coarse­grained, smoothly cemented test with four inflated chambers in the last whorl separated by depressed sutures. Remarks. Specimens are often compressed and deformed through diagenesis. Range and Occurrence. Late Cretaceous in Well CM10, Casamance Shelf, Senegal.

ACKNOWLEDGEMENTS We are especially grateful to two anonymous reviewers and to Malcolm Hart for reviewing the manuscript. We extend our thanks to Uwe Pflaumann

for providing access to material from DSDP Site 369 and to the staff of the SEM Lab and Photographic Unit of the Institut flir Geowissenschaften at the Christian Albrechts University in Kiel for their invaluable technical support. We thank the Deutsche Forschungsgemeinschaft (Grant Ku649-2 "Equatorial Atlantic Gateways") for financial support. AELH gratefully acknowledges support of a Royal Society European Exchange Fellowship at Kiel University.

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Upper Cretaceous agglutinated foraminifera of the western African Margin 139

Table 1. Coded matrix used in the correspondence analysis showing frequency counts for 144 taxa of agglutinated foraminifera and 177 samples.

959~48R-6. 28-31 em 959-48R-CC 959-49Al, 28-31 em 959·49A·', 69-72 em 959-49A-l, 110-114 em 959-49A-2. 27-30 em 959-49A-3, 27-30 em 959-49R-4, 27-30 em 959-49R-4, 69-72 em 959-49R-S, 27-31 em 959-49A-6. 27-30 em SS9-SOR-l, 27-30 em SS9-SOR-',70-73cm 959-S0R-2. 26-29 em 9S9-S0A-3, 28-31 em 959-S0R-4. 26·29 em 959-S0R-4, 68·71 em SS9-S0A·5, 30-34 em 959-S1R-3, 28-31 em 959-S2A-', 23-27 em 959-S2A-" 29-33 em 959-S2R-l, 67·71 em 959·52A·2, 25-27 em 959·52R·3, 27-31 em 959-52R·4, 30-33 em 959-52R-4, 45·48 em 959-S3R-5, 29-33 em 959-54R-l. 30-34 em 959·55R·S, 35-37 em 959·55R· 7, 36-38 em 9S9-S6A·1,127-132em 959·57R-l, 28-32 em 959-57A-1,134-137em 959-57A-2, 30-34 em 959-57R-3, 30-34 em 959-57A-4, 14·17 em 9S9·57A-4, 29-33 em 9S9-57A-5, 27-31 em 9S9-58A-1, 58-81 em 9S9-58A-1, 70·72 em 959-58R-1, 110-114 em 959-58R·3, 113-116 em 959-58R·4, 28-31 em 9S9-S8R-4, 67-71 em 959-59R·1. 25-30 em 959-59R-1, 30-34 em 959-59R-1, 62-67 em 959-59R·2, 27-32 em 959-59R-2. 32·36 em 959-59A-3. 22-27 em 959-59A-4. 30-35 em 9S9-59R-4, 75-80 em 959-59-5, 29·34R em 9S9-60A-l, 22·24 em 959-60R-2, 26-28 em 959-60R-3, 24-26 em 959-60A-4, 24-27 em 959·60A-4, 68-73 em 9S9-60A-4, 109-113 em 9S9-60A-5, 17-21 em 959-61 A-2, 61-65 em 959-63A·l, 38-40 em 959-63A·l, 69-72 em 959-63R-4, 24-26 em 959-63A-4. 98-100 em 959-63A-5, 59-62 em 959-63A-6, 39-42 em 959-64A-l, 25-28 em 959-64A-2, 3-6 em 959-64R-2, 30-34 em 959-64R-3, 32-35 em 959-64R-4, 32-35 em 959-64A-5, 13-15 em 959-64R-6, 9-12 em 959-65R-', 28-32 em 959-65R-', 49-52 em 959-65R-2, 28-32 959-65R-3, 32-36 367-14R-4. 95 em 367-15R·1, 141 em 367-15A-2.111 em 367 -15A-3. 97 em 367-15R·4, 106 em 367-15R-5, 39 em 367-16R-2. 102 em 367-16R-3. 124 em 367-16R-4, 117 em 367-16R-5. 110 em 367-16R-6, 131 em 367-16R-CC

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140 Ann Holboum & Wolfgang Kuhnt

Table 1 (continued). Coded matrix used in the correspondence analysis showing frequency counts for 144 taxa of agglutinated foraminifera and 177 samples.

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959-48R-6, 28-31 c 95948R-CC 959-49Rl. 28-31 C 95949R-l,69·72 959~49R"1, 110-114 959-49H-2,27·30 959·49R-3,27-30 959·49R-4,27-30

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959·50R·5,30·34 959·5, A·3, 28·3' 959-52R-l,23-27 959-52R-l. 29-33 959-52A-l,67-71 C 959-S2R-2, 25-27 c 9sg.52R-~, 27-31 c 959-52R4. 30-33 c 959-52R-4. 45-48 c \l59·53R·5. 29·33

-1,30-34 959·55R·5.35·37 959-55R·7.36·38 959·5:6R·l,I2]-132 959·57R·1. 28-32 959-57R·1. 134·137 959-57R·2. 30·34 959-57R·3, 30·34 959-S7A-4. 14-17 959·57R-4. 29·33 9SS.S7R-5,27-31 959-58R-1, 58-i)1 959-58R-1. 70-72 959-SBR-1,110-114 9Sg..5BR-3,113-116 959-58R-4,28·31 959·58R-4.67·71 959·59R·1.25-30 959·59R·1. 30-34 959·59R·1. 62-67 959·59R·2,27·32 959·59R·2, 32·36 959-59R·3, 22·27 c 959·59R·4, 30·35 959·59R·4. 75·80 r!

959·59·5, 29·34R 959·60R·1. 22·24 c 959·60R-2. 26·28 c 959·60R-3. 24·26 c 959·60H-4. 24·27 c 959-SOR-4. 68·73 c 959·6(JR·4,109·113 959·60R·5, 17·21 e 959-61R·2, 61·65 c~ 959.£3R·1, 38·40 crt 959-63R-1, 69·72 c~ , 959-63R-4, 24-26 c~ 959-63f\-4. 913-100 G

: 95!HJ3R·5. 59·62 cr, : 95!Hl3R-6. 39·42 c<1 : 959-64R·1. 25·28 c<1 :959·64R·2.3.6cm : : 959·64R·2. 3(}-34 : 959·64R·3. 32·35 959·64R-4. 32·35 959·64R·5, 13-15 959-64R·6, 9·12 etn 959·65R·1, 213-32 959-65R·1, 49·52 959·65A·2, 29·32 959·65A·3.32·36 367-14A-4,95em 367-15R·1. 141 em 367·15R-2. 111 em 367-15R-3,97em 367-15R-4, 106 em 367·15R·5, 39 em 367·16R·2, 102 em 367·1-6R·3, 124 em 367-16R-4, 117 em 367-16R-5, 110 em 367-16R-6, 131 em 367-16R C

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Upper Cretaceous agglutinated foraminifera of the western African Margin 141

Table 1 (continued). Coded matrix used in the correspondence analysis showing frequency counts for 144 taxa of agglutinated foraminifera and 177 samples.

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Ashaka 3/3-25 Ashaka 3/3-26A Ashaka 313-268

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Pindiga 413-8

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Pindiga 413·18 CM2' 1112 CM2C2 1134-1135 CM2' 1306 CM2' 1408 CM2' 1516 CM2' 1606 CM2' 1654 CM2' 1713 CM2C3 1803 CM2C3 1970·1971 • c CM2C3 1971-1972 a a a CM2C3 A1972_8-1973.6 f CM2C3 61972.8-1973.6 CM2C3 1973.8-1974.8 CM2C3 1975.8-1976.8 a c CM2C3 1976.6-1977.5 a CM2C3 1977.5·1978.4 a CM2C3 1979.5-1980.5 a CM2C3 1980.5-1981.5 CM2C3 1981.6-1982 CM2C3 1983.6-1984.4 CM2C3 1984.4-1985.4 CM2C3 1985.4-1986.2 CM2' 2093 CM2C4 2348-2349 CM2C4 2349-2350 CM2C4 2357-2358 CM4' 900.00 CM4' 1025.00 CM.' 1120.00 CM4' 1206.00 CM.' 1286.00 CM4' 1293.00 CM4' 1318.00 CM4' 1322.00 CM4' 1330.00

:CM4Cl 1374.00 iCM4Cl 1757.65-1758.58 ICM4Cl 1758.58-1759.48 iCM4Cl AI759.48-1760.40 :CM4Cl 81759.48-1760.40 CM4Cl 1764.00-1765.30 CM10Cl 1525-1526 CM10C2 1731-1732 CM10C2 1732-1733 CM10C2 1734-1735 CM10C2 1735-1736 CM10C3 2000-2001 CM10C3 2001-2002 CM10C3 2003-2004 CM10 C3 2005-2008 CM10 C4 2275-2276 CM10 C4 2276-2277 CM10C4 2278-2279 CM10 C4 2279-2280 CM10 C4 2280-2281 CM10 C4 2261-2282 CM10C5 2452-2453 CMIOC5 2453-2454 CM10C5 2454-2455 CMIOC5 2455-2456 GMl0' 2502 CMIO' 2612

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142 Ann I-Iolboum & Wolfgang Kuhnt

Plate 1. Tarfay.1 Basin (height of specimens in I'm). I. No/lu.l rubus/I! (Gr'l.)'bowskil. (1850 I'm). 5.1mplc TAli 37. 2,., b. No/Ilia rohlfs/a (Grzybowski). (2900 Ilm), 5.1mplc TA li 37.3. HIII'/ol'llrfI[<lltloidl"$ A. (520 #1m), 5.1Jnplc T AI-J 39;1., 4. Rl'Opilll.T sp., (750 p.m). S.,mplc TAH 63. 5. Hllplol,hmSllloldts A, (520 11m). 5.lmpli' TAH 39.\, 6. HIl/I/opilrasmoirirs A, (560 Ilm), 5.1mplc TAl-I 56.7. HOI,/ophragllloidts A, (450 I'm), 5.1mple TAH 56. 8. HIIJ'lopr,m,~lIIoll'd /1" (280 11m), S.,mp,lc TA I-f 41. 9. Tritoxin c-npilosa (Cushman), (1020 /1m), Samplt· TAH 32. 10. Dorollwi sp. 1, (630 jim), S.'m~lc Til l 1 36. 11 . Oorolh ia sp. 1, (780pm), $<tmplc TAH 36. 12. Tfllllxin CII/IlIOi'11 (Cushm;II\). (1360 11m), S,lmplc TAli 37. 13. T" IIIX;II CtJllitOSll (Cllshm~Il ), (1020 I'm), Silmple TAH 32.

Upper Cretaceous agglutinated foraminifera of the western African Margin 143

Plate 2. Tarfaya Basin (height of specimens in /lm) . 1. Trila:ria capiloM (CushlTI<ln), (1150 14m), Sample TAH 32. 2. Trila:ria trlpi/osa (Cushman), (1220 14m), Sample T AH 32. 3. Trilaxia capiloM (Cushmiln), (1470 pm), S<lInple TAH 32. 4. Spiropiecliliel/rl erelOM (Cushmiln), (590 pm), Sample T AH 39. 5. Spiropieclilidia errlosa (Cushm~n), (470 14m), Silmple TAH 39. 6. 5plropirclillflla erelOM (Cushman), (630 pm), Sample TAH 39. 7. Spirol'ieClillel/Jj err/OM (Cushman), (490 /1m), Sample T AH 39.8. Gaudn/itm errlart'a (Karrer), (930 14m), Sample TAH 39. 9. Galldryilla crI'/ac('fI (Karrer), (900 pm), Sample TAH 39. 10. PSl'lIdoclalllllilw dal'rl/a Cushman, (1930 /1m), Sample T AH 39. 11. P$l'lulof!lIlJlIlillll clilm/a Cushman, (1980 I'm), S~mple T AH 39. 12. Glilldryinrl erl'faull (Karrer), (870 I'm), Sample TAH 39. 13. Marssolll'lIa OXl/COIIJJ (Reuss), (580 pm), S<lmple TAH 39. 14. Mllrssollellil OXyCOll1l (Reuss), (530 pm). Sample TAB 39. 15. Marssol1ellll OXyCOIUl (I{euss), (580 I'm), Sample T AH 39.

'" Ann Holbounl & Wolfgang Kuhnl

Plate 3. C.1s;lmancc Shelf, offshore Senegal (height of specimens in ~Ill). la, b. GllIIrlryiua frleviSMa Frilnke, (930 11m), Sampll' CMI O-C4, 1"2. 2. GalldrllilJll pyramidala (lIshm.m, (510 J'1ll). S~mplc CMJO-C4, 1"2. 3a, b. GIll/Ifryi1ll1 11I1'1"$I1/a Franke, (460 I'm), S.,mplc CMlO-C4, 12.4. Carlliryimi pyra/uilln/a Cushman, (660 'tm), S.,mplc CMlO-C4, 1'2. 5. AIIW/()(I!SCII$ sp., (450 I'm). Sample CM10-C2, n. 6. HIl'IIQpltfll~IIIDidc5 sp. 2, (680 J'1l\). S.,mplc CM2-C3, 1976.6-}977.5 em. 7. HaJl/opllragIllCJid~ sp. 2, (590 j.un). Sample CM1Q·CI. Tl. 8.I\III/IIobacrdi/t'S sp. 2, (770 Jotm), Sample CM2-C3, 1971-\972 em. 9. ?Hllpfophragmoirlrs sp. 1, (870 101m), 5.1mple CM10-0. T6. 10.1, b. ?Hilplophr(l:~m()idl'S loP. 1, (450 p.m), Sample CMIO-O, T6.

Upper Cretaceous agglutinated foram inifera of the western African l\'largin 145

Plate <I. Casamance Shelf, offshore Senegal (height of specimens in pm) 1. HYI',efnmmlllll sp., (490 pm), S.1mple CMlO-0,1'3_ 2. Rtophax d. dupln: Grzybowski, (830 pm), 5.1mpJe CMID-C-I, n. 3. Rl'opl", .. d.lfl/plt'x Grtybowski. (1080 pm), 5.!mple CMI0-CI, 1'3. 4. RtolJluu SlOOOsll5 Sliter, (640 pm), 5<l.mple CMI0-C2, n . 5. H!JII~rlllll",i"n sp., (260 JIm), Sample CMrD-CS, TI . 6. JUmbdallllllllla sp., (650 I'm). Sample CM2-C3, 19n.S·1973.6 cm. 7. Allllllolmrllllll'$ sp. I, (530 I'm), Sample CM2·C3, 197\-19n em. 8. Allllllooocullt,'S sp. I, (520 pm), Sample CM2·C3, 1976.6-1977.5 em. 9. t1mmobnwlilts sp. I, (630 I'm). Sample CM2-0, 1976.6-1977.5 em. 10. -TI'\/ulario1'sis" sp. 3 (330 pm), Sample CMlO·C2, n , 11 , ~TI',\'llIlllrioJ'$i5" sp. 3 (520 pm), 5.1mple CMlO-C2, 2. 12, "Tt:dlllarioilSl~~ sp. 2, (560 pm), Sample CM10:C3, n. 13. "Tt.1: tlllariojlsis" sp. 2, (570 pm), Sample CMlo.:C3, n. 14. "Tt'.rllllnrwl'sis" sp. 1, (260 JIm), Silmple CMlO-C5, 1'3. 15. "Texlllinriops/s" sp.. I , (300 pm), Sample C}.I1D-C5, 1'3. 16. Troclrummiml sp. I, (300 pm), 5.1mpie CMIO-eJ, T6. 17. Trodmmmil!(/ sp. 1, (430 pm), Sample CMI().O, T6. 18. PI«li,Hlleliis (Grzybowski), (640 pm), 5.'lmple CM2-C3, 1971-1972 em. 19. Splrop/«Iammmn cllicotUlII ulicker, (380 pm), 5.1mple CMIO-C5, n .

146 Ann Holboum & Wolfgang Kuhnt

Plate 5. Casamil nce Shelf, offshore Senegal (height of specimens in ~m). 1. Ammomarsillulhlll sp. I, (320 /lm), Sample CMID-D, T6. 2. AmmOlUafr;:illlllillll sp. 1, (330 pm), 5.1mplc e M 10-(3, T6. 3. Ammomorgilllllil111 sp. I, (330 pm). 5.1mple CMI0--C3, T6. 4.1, b. I\lIIlIIolilml 1I~llljlg1l!n (960 pm), 5.lmpll.' CM2-C3. 1985.4 -1986.2cm. 5. 1\1II111(lliwlI IIkalaglllll (660 pm), Sample CM2-C3, 1976.6-}977.5 em. 6, Ammolium IIkillagHIll (650 pm), S"lnple CM2-C3, 1976.6-1977.5 em. 7. Allllllotimll IIka/aglllll (850 pm), 5.1mpil.' CM2·C3. 1976.6-1977.5 em. 8.1, b. KulSl'l1t'lIn sp. I, (540 11m), Sample CM2·C3, 1979.5-\980.5cm. 9.1, b. K,iI$i'(1t1l1l sp. I, (390 l'm), 5.1mple CM2·C3, 1979.S-19SO.Scm. 10. KIII;:(ll.!lIn sp. I, (330 I'm). Si!mple 0. .. 12-0, 1971-19n em. 11. KJII5('w//o sp. I, (510 11m), Sample CM2·C3, 1971·19n em. 12. Kuly~1I11 sp. I, (440 Ilm), Sample CM2·C3, 1976.6· 19n.s em. 13. Kuls..'W1I1l sp. I. (440 /lm), Sample CM2-eJ, 1976.6·19n.s em.

Upper Cretaceous agglutinated foraminifer.1 of the western African Margin 147

Plate 6. Benue Trough, Nige ria (height o f specimens in jJ.m). H . Trochalll1l1iud sp., (230 pm, 270 pm, 300 JIm. 310 /lm), &lmple 3/3-H, Ashaka quarTI" 5. ?Kulu-wllu sp., (560 pill), 5.1mple 3/3-1·1, Ashaka quarry. 6-8. Ammobnculiid sp., (630 JIm, 890 pm, 950 pm), 5.1mple'3/J· 4, Ashaka quarry. 9-10. Ammolirrl/! IIIm/lIgum Pcttcrs, (570 pm, 570 pm, 700 pm, 750 /lm),$ample 4/3-18, Pindiga section. '13. Amlllo/irllll sp. (intermediate foml bcwecn A bomlllll ilnd A /l1ar/l1gw,,), (330 JIm), Sample 3/3-265, Ashakil qUilrry. 14-15. AII11110UUHI sp., (490 /1m, 520 /lm), Sall'lpie 3/3-14, Ashaka quarry. 16·18. Ammo/Krcultlts sp., (480 pm, 360 /1m, 460 /lm), 5.:Jmplc 3/3·265, Ashaka quarry.

148 Ann Holboum & Wolfgang Kuhn!

Pl a te 7. Benue Trough, Nigeria (height of specimens in Jim). 1. Amlllolilllll sp., (720 i-'m) . S<lmple 4/3-4, Pindiga section. 2-4. AmmotiulII bOr/wlII Petters, (390 /ln1, 370 /l0l, 400 /1m), Sample 3/3-266, Ashakcl gl1<1rry. 5. Ammotirllll h0rl1l1111 Petters, (360 Jim), Sample 3/3-14, Ashaka quarry. 6-8. Reophnx sp., (31O J1m, 290 11m, 420 !-lin), Sample 3/3-266, Ashaka quarry. 9-16. AII!1I1obaculites sp., (740 Jlrn, 720 Jim, 730 Illll, 720 /-t0l, 730 11m, 720 11m, 630 11m, 940 11m), Sample 4/3-4, Pindiga section.